Clinical, haematological and biochemical findings in foals with neonatal Equine herpesvirus-1 infection compared with septic and premature foals

A retrospective multicentre study comparing historical, clinical, haematolo gical, acid-base and biochemical findings of foals with Equine herpesvirus- 1 (EHV-1) infection, septicaemia or prematurity was performed to determine if early diagnosis of EHV-1 foals was possible. Fifty-three foals were stud ied and were assigned to one of 2 groups: herpes positive (n = 14) or herpe s negative (n = 39). The latter group included 20 septic, 11 premature, and 8 premature and septic foals. The presence of herpes antigen was confirmed by immunoperoxidase histochemical staining of tissues from necropsied foal s. A nonparametric statistical analysis followed by a backwards elimination logistic regression was performed to establish a model at a P value of <0. 05. All herpes positive foals died, while 47% (9/19) of the septic foals surviv ed. Based upon our analysis, herpes positive foals were more likely to have total white blood cell counts less than 3 x 10(9)/l and to be icteric as c ompared to the septic and premature foals. Despite profound hepatic necrosi s in the herpes positive foals, liver enzymes were not elevated and were no t significantly different from the controls.